Index: subversion/include/svn_types.h
===================================================================
--- subversion/include/svn_types.h	(revision 8132)
+++ subversion/include/svn_types.h	(working copy)
@@ -98,14 +98,24 @@
 #define SVN_IS_VALID_REVNUM(n) ((n) >= 0)
 
 /** The 'official' invalid revision num */
-#define SVN_INVALID_REVNUM ((svn_revnum_t) -1)
+#define SVN_INVALID_REVNUM_VALUE -1
 
+/** Macro C code should use for the invalid revision as it handles
+ * typecasting for you.
+ */
+#define SVN_INVALID_REVNUM ((svn_revnum_t) SVN_INVALID_REVNUM_VALUE)
+
 /** Not really invalid...just unimportant -- one day, this can be its
  * own unique value, for now, just make it the same as
  * @c SVN_INVALID_REVNUM.
  */
-#define SVN_IGNORED_REVNUM ((svn_revnum_t) -1) 
+#define SVN_IGNORED_REVNUM_VALUE -1
 
+/** Macro C code should use for the ignored revision as it handles
+ * typecasting for you.
+ */
+#define SVN_IGNORED_REVNUM ((svn_revnum_t) SVN_IGNORED_REVNUM_VALUE) 
+
 /** Convert null-terminated C string @a str to a revision number. */
 #define SVN_STR_TO_REV(str) ((svn_revnum_t) atol(str))